Electric lamp



A ril 13, 1937. H. ASMUSSEN ELECTRIC LAMP Filed Aug. 21, 1936 Heirwich Asm ssen,

His Attor'neg Patented Apr. 13, 1937 UNITED STATES ELECTRIC LAMP Heinrich Asmussen,

Berlin-Steglitz, Germany,

assignor to General Electric Company, a corporation of New York Application August 21, 1936, Serial No. 97,263

In Germany August 29, 1935 2 Claims.

My invention relates to electric lamps and similar devices comprising a bulb having an electrical energy translation element such as a filament sealed therein and a base mounted on said bulb. More particularly, my invention relates to bases for said devices and still more particularly to so-called mechan cal bases in which the usual cement which unites the base to the glass bulb is eliminated.

Mechanical bases have been proposed in which the base is held on the bulb solely by means of a leading-in wire of high tensile strength and is prevented from turning by corresponding engagement means in the base and bulb. The leading-in wire is stretched tightly between the usual stem press of the lamp and the base and is attached to the latter, preferably by solder. One or more longitudinal grooves in the neck of the bulb and indentations in the base shell provide the engagement means for preventing rotation of these parts. A mechanical base of this construction is shown in my Patent 2,014,220, which issued September 10, 1935. With this construction, the base and bulb neck must cori5 respond in size so closely that there is no play therebetween and the base shell slides on the bulb neck; otherwise, a slight back and forth lateral movement or wabble of the base is possible. However, the occurring friction makes it quite diflicult to slide the base onto the bulb at assembly when these parts fit properly, and many lamps are broken. For this reason, it has been customary to permit a certain amount of play between the base and bulb neck, which has the disadvantages already referred to.

To prevent the base from wabbling, a thin filling medium--preferably a layer of shellac-is placed between the inner surface ofthe base and the neck of the bulb. The shellac is placed either on the inner surface of the base or better still on the neck of the bulb as it lubricates and facilitates mounting the base. An alcoholic shellac solution is preferably used, which leaves a very thin layer of shellac when the alcohol evaporates, as this is suificient to compensate for the small difference in dimensions and fills com- 1raillelikaely the narrow gap between the base and the The thin layer of shellac is in addition a binding medium but does not in any way constitute a substitute for cement for the adhesive qualities of the shellac layer are slight compared to those of cement and, on the other hand, there is very much less shellac than cement used. The addition of the shellac does not reduce the advantages of the mechanical base which in itself provides for the elimination of the heating operation normally used to cause the basing cement to harden and all other disadvantages traceable to the basing cement.

In the drawing, Fig. 1 is an elevation partially in section of an incandescent lamp having a mechanical base of my invention; Fig. 2 is a side elevation of the base at right angles to Fig. 1; and Figs. 3 and 4 are a section through and a side elevation at right angles thereto respectively of a modified mechanical base of my invention.

In Fig. 1, the incandescent lamp is comprised of a bulb l having a filament sealed therein and attached to the inner ends of the leading-in wires I2 and I3. The leading-in wires l2 and I3 pass through the stem press portion M of the stem tube I5 which supports the mid-portion of the filament through the arbor l6 and the support wires IT. The neck portion l8 of the bulb I ll is formed particularly for the mechanical base l9 and is provided with a neck portion which fits into the threaded shell 2| thereof and with a pair of oppositely disposed grooves 22 which register with indentations 23 (Figs. 1 and 2) in the said shell 2|. The base I9 is comprised of the shell 2|, the metal eyelet 24 and the insulation 25 and is slipped over the neck portion 20 of the bulb l0 after it is first coated with a light alcohol and shellac solution. The alcohol evaporates, leaving the thin shellac layer 26 only a few fractions of a millimeter in thickness which fills in between the base shell 2| and the bulb neck 20 so that the base l9 can not wabble. One of theleading-in wires I2 is bent back into one of the grooves 22 and under the rim of the base shell 2| and is soldered or welded thereto in the indentation 23. The other of said leading-in wires l3, which is particularly strong, passes through a central hole in the insulation 25 and the eyelet 24 and is either soldered or welded to said eyelet 24.

In the species of my invention shown in Figs. 3 and 4, the neck portion 21 of the bulb is formed into the screw threads 28 and the boss 29. The screw threads 28 support the lamp when they are screwed into the so-called standard socket. The boss 28 supports the base 30 which is comprised of the metal shell 3|, the insulation 32 and the eyelet 33. As in the previous instance, the shell 3| is indented at two oppositely disposed points 34 which register with longitudinal grooves in the boss 29 and prevent the base 30 from turning. In this case, the shell 3| is made to fit snugly onto the lamp by a layer 35 of shellac placed on the inner surface of the said shell 3| in such a position as to engage the boss 29. The leading-in wires I2 and I3 are attached to the 5 shell 3| and the eyelet 33 respectively of the base 30 which is held in place on the lamp by the strength of leading-in wire l3 as disclosed in my patent hereinbefore referred to.

What I claim as new and desire to secure by 10 Letters Patent of the United States is:

20 from wabbling, and a leading-in wi-re having a portion thereof sealed ina portion of the bulb and an end thereof secured fixedly to said base end eyelet, said leading-in wire being tightly stretched between said bulb and base and constituting the sole means for holding said base firmly on said bulb neck against longitudinal displacement.

2. An electric device comprising a bulb having a neck portion and a base comprising a metal shell surrounding at least a portion of the bulb neck and an end eyelet, said bulb neck and base shell having interlocking engagement means therein for preventing relative rotation therebetween, a layer of shellac between said bulb neck and said base shell for'preventing the base from wabbling, and a leading-in wire having a por-- tion thereof sealed in a portion of the bulb and an end thereof secured fixedly to said base end eyelet, said leading-in wire being tightly stretched between said bulb and base and con stituting the sole means for holding said base firmly on said bulb neck against longitudinal dlsplacement.

HEINRICH ASMUSSEN. 

